(a) Field of the Invention
The present invention relates to a Liquid Crystal Display (LCD) and a driving method thereof. More specifically, the present invention relates to an LCD and a driving method for providing compensated data voltage in order to improve a response time of the liquid crystal.
(b) Description of the Related Art
As personal computers (PC) and televisions have recently become lighter in weight and slimmer in thickness, lighter and slimmer display devices have also been in great demands. Accordingly, flat panel type displays such as an LCD instead of a cathode ray tube (CRT) have been developed.
In the LCD, a liquid crystal layer having anisotropic permittivity is injected between two substrates of a panel, and the light transmittivity of the panel is controlled by applying and controlling the electric field. Desired images are obtained in such a manner. An LCD is one of the most commonly used portable flat panel display devices. In particular, the thin film transistor liquid crystal display (TFT-LCD) employing the TFT as a switching element is most widely used.
As more TFT-LCDs have been used as display devices of computers and televisions, it becomes increasingly important to implement moving pictures on the TFT-LCD. However, conventional TFT-LCDs have a relatively slow response speed. So it is difficult to implement moving pictures on the conventional TFT-LCD. To solve the problem of the slow response speed, different type of TFT-LCD that uses the optically compensated band (OCB) mode or ferro-electric liquid crystal (FLC) has been developed.
However, the structure of the conventional TFT-LCD panel must be modified to use the OCB mode or the FLC.
It is an object of the present invention to enhance the response speed of the liquid crystal by modifying the liquid crystal driving method without modifying the structure of the TFT-LCD.
In one aspect of the present invention, an LCD comprises: a data gray signal modifier for receiving gray signals from a data gray signal source, and outputting modification gray signals by considering gray signals of present and previous frames; a data driver for changing the modification gray signals into corresponding data voltages and outputting image signals; a gate driver for sequentially supplying scanning signals; and an LCD panel comprising a plurality of gate lines for transmitting the scanning signals; a plurality of data lines, being insulated from the gate lines and crossing them, for transmitting the image signals; and a plurality of pixels, formed by an area surrounded by the gate lines and data lines and arranged as a matrix pattern, having switching elements connected to the gate lines and data lines.
The data gray signal modifier comprises: a frame storage device for receiving the gray signals from the data gray signal source, storing the gray signals during a single frame, and outputting the same; a controller for controlling writing and reading the gray signals of the frame storage device; and a data gray signal converter for considering the gray signals of a present frame transmitted by the data gray signal source and the gray signals of a previous frame transmitted by the frame storage device, and outputting the modification gray signals.
The LCD further comprises: a combiner for receiving the gray signals from the data gray signal source, combining the gray signals to be synchronized with the clock signal frequency with which the controller is synchronized, and outputting the combined gray signals to the frame storage device and the data gray signal converter; and a divider for dividing the gray signals output by the data gray signal converter so as to be synchronized with the frequency with which the gray signals transmitted by the data gray signal source are synchronized.
In another aspect of the present invention, in an LCD driving method comprising a plurality of gate lines; a plurality of data lines being insulated from the gate lines and crossing them; and a plurality of pixels, formed by an area surrounded by the gate lines and data lines and arranged as a matrix pattern, having switching elements connected to the gate lines and data lines, an LCD driving method comprises: (a) sequentially supplying scanning signals to the gate lines; (b) receiving image signals from an image signal source, and generating modification image signals by considering image signals of present and previous frames; and (c) supplying data voltages corresponding to the generated modification image signals to the data lines.